In vitro/in vivo evaluation of 3D bioprinted silk fibroin hydrogels for IBD: A dual mesalazine and TNF-α siRNA approach

Inflammatory bowel disease (IBD) is a chronic, relapsing disease that poses significant challenges in treatment. This study aimed to develop silk fibroin-based mesalazine and chitosan:TNF-α siRNA polyplex-loaded, 3D bioprinted hydrogels for the oral treatment of IBD. For this purpose, bioink formulations composed of silk fibroin, hyaluronic acid, and sodium alginate were optimized. A chitosan:TNF-α siRNA polyplex was also formulated at a 40:1 chitosan-to-siRNA ratio. Hydrogel formulations were fabricated using 3D bioprinting and characterized in terms of compatibility, thermal stability, swelling behavior, degradation, mechanical properties, and mucoadhesion to both healthy and IBD-induced colon tissues. The optimized oral hydrogel (H-M-P12) demonstrated a swelling index of 366±67 % and underwent 31.2 % degradation after 24 h in vitro. Mesalazine and TNF-α siRNA exhibited a sustained release profile from the hydrogels. Cytotoxicity studies confirmed the biocompatibility of the hydrogels and a TNF-α gene silencing efficiency of 46.53 % was obtained. In vivo studies in a Balb/c mouse model of IBD revealed significant improvements in physiological parameters, macroscopic and microscopic morphology, and biochemical markers following treatment with the developed hydrogels. These findings suggest that silk fibroin-based hydrogels incorporating mesalazine and chitosan/TNF-α siRNA polyplex, produced via 3D bioprinting, hold promise as an effective therapeutic approach for IBD.